Method of forming metal layer used in the fabrication of semiconductor device

ABSTRACT

A method of forming a metal layer on the conductive region of a semiconductor device includes concurrently supplying a mixture gas including a hydrogen gas and a metal chloride compound gas, and a purge gas into a chamber having a sealed space for a predetermined time, thereby forming a first metal layer on the semiconductor substrate, using a plasma enhanced chemical vapor deposition (PECVD) method. The hydrogen gas and metal chloride gases are thereafter alternately supplied for a predetermined time while the purge gas is continuously supplied into the chamber, thereby forming a second metal layer on the first metal layer, using a PECVD method. Deterioration of semiconductor devices due to high heat by a conventional CVD method can be prevented using a PECVD method as a low temperature process, thereby improving a production yield.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. patent application Ser. No.11/245,366, filed Oct. 5, 2005, now pending, which claims the benefit ofKorean Patent Application No. 10-2004-0082027, filed Oct. 14, 2004, thedisclosures of which are hereby incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a method of fabricating a semiconductordevice, and more particularly, to a method of forming a metal layer inthe fabrication of a semiconductor device.

2. Discussion of Related Art

With improvements in semiconductor manufacturing, design rules for suchdevices are continually being scaled down. Accordingly, the elementsforming such devices—including transistor channel length,interconnection width and distance, and contact pad size—are gettingsmaller and smaller.

But size reduction of these parts brings forth new problems. Contactpads, for instance, need to provide a low resistance contact butresistance increases and the part size is reduced. To address thisdifficulty, scaled down pads have been formed using a metal silicidelayer. Such a metal silicide layer functions as an ohmic layer providinga low resistance interface between a silicon substrate and a metal layerformed thereon. Further, the metal silicide layer functions as adiffusion barrier layer for preventing two discrete materials from beingdiffused into the other one—that is, between a metal layer and anunderneath semiconductor region, or between two metal layers in amultiple metal system.

The metal silicide layer is typically composed of titanium silicide(TiSi₂) or a VIII group silicide, for example, PtSi₂, PdSi₂, CoSi₂,NiSi₂, and the like, with titanium silicide or cobalt silicide typicallybeing used in a semiconductor device below 0.25 μm.

In a conventional fabrication method, and after a refractory metal layerhas been deposited by a sputtering method, an annealing process such asrapid thermal process (RTP) is performed so as to form a metal silicidelayer at the interface between the refractory metal layer and an exposedsilicon region. Sputtering, however, has a drawback in that it resultsin poor step coverage by the metal layer within a contact hole having ahigh depth-to-opening aspect ratio. That is, the deeper the hole and thenarrower the opening, the worse the coverage by sputtering up to apredetermined height from the bottom of the contact hole. Furthermore,an insufficient metal silicide layer is formed on the bottom of thecontact hole without a subsequent annealing process.

In order to solve the problem of the poor step coverage in thesputtering method, a chemical vapor deposition (CVD) or plasma-enhancedchemical vapor deposition (PECVD) is used to deposit a refractory metallayer and form a metal silicide layer concurrently with the depositionof the refractory metal layer. Formation of the metal silicide layerinside a high and narrow contact hole is improved even without asubsequent annealing process because the refractory metal layer directlyreacts with the silicon of an active region. The result of the CVD orPECVD methods are excellent step coverage, which simplifies thefabrication processes. Such a method of forming a metal layer using theCVD or the PECVD method as above is disclosed in U.S. Pat. No.6,589,873.

FIG. 1 is a sectional view of a semiconductor device illustrating aconventional method of forming a metal layer.

Referring to FIG. 1, the conventional method of forming a metal layerincludes supplying a metal chloride compound (TiCl₄) into a PECVDchamber concurrently with a hydrogen gas and an argon gas beforeapplying a RF power, thereby forming a metal layer inside a contact hole311.

Here, the contact hole 311 selectively exposes the surface ofpolysilicon or silicon substrate doped with conductive impurities usedas a conductive layer electrically connected to the metal layer from aninterlayer insulating layer 309. For example, a metal oxidesemiconductor field effect transistor (MOSFET) is formed below thecontact hole 311, and the conductive layer exposed by the contact holebecomes a polysilicon gate electrode or source/drain regions of asilicon substrate.

At this time, if a high RF power is used in forming the metal layer, thegate electrode connected to the metal layer or the interlayer insulatinglayer is charged by the RF power, so that a gate insulating layer formedbelow the gate electrode may be damaged. This damage may be prevented byforming the metal layer without applying RF power at the initial time offorming the metal layer.

However, the conventional method of forming a metal layer without RFpower has problems as follows.

First, a high temperature (about 1000° C.) is required in a CVD processto promote a chemical reaction between hydrogen and metal chloridecompound. Application of high temperature, however, may damage thesemiconductor device and reduce the production yield for such devicesduring mass manufacturing.

Secondly, premature bonding of the hydrogen and silicon to the surfaceof the polysilicon or silicon substrate may occur in the PECVD processto portions exposed by the contact hole 311. The bonded hydrogen andsilicon acts as defects in forming metal silicide which results in anincrease in the contact resistances of the conductive layer and themetal layer so that electrical characteristics of a semiconductor devicemay be deteriorated.

Accordingly, the need exists for a method of forming a contact within acontact hole that overcomes the drawbacks of the prior art.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide the method offorming a metal layer including concurrently supplying a mixture gasincluding a hydrogen gas and a metal chloride compound gas, and a purgegas into a chamber having a sealed space for a predetermined time,thereby forming a first metal layer on a semiconductor substrate havinga conductive layer exposed, using a PECVD method; and supplying thehydrogen gas and the metal chloride compound gas alternately for apredetermined time while the purge gas is continuously supplied into thechamber, thereby forming a second metal layer on the first metal layer,using a PECVD method.

In another aspect of the present invention, exemplary embodiments of thepresent invention provide a method of fabricating a semiconductor deviceincluding forming a silicon conductive layer selectively exposed by aninterlayer insulating layer electrically insulating a semiconductorsubstrate having plural elements formed thereon; supplying a mixture gasincluding a hydrogen gas and a metal chloride compound gas, and a purgegas into a chamber having a sealed space concurrently for apredetermined time, thereby forming a first metal layer on theconductive layer, using a PECVD method; and supplying the hydrogen gasand the metal chloride compound gas alternately for a predetermined timewhile the purge gas is continuously supplied into the chamber, therebyforming a second metal layer on the first metal layer, using a PECVDmethod.

Exemplary embodiments of the present invention provide a method offorming a metal layer including alternately supplying a metal chloridecompound gas and a hydrogen gas into a chamber while a purge gas issupplied at a predetermined flow rate into the chamber, thereby forminga metal layer with a predetermined thickness by a PECVD method, whereina supplying time of the hydrogen gas is gradually increased.

In another aspect of the present invention, exemplary embodiments of thepresent invention provide a method of fabricating a semiconductor deviceincluding forming a silicon conductive layer selectively exposed by aninterlayer insulating layer electrically insulating a semiconductorsubstrate having plural elements formed thereon; and alternatelysupplying a metal chloride compound gas and a hydrogen gas into achamber while a purge gas is supplied at a predetermined flow rate intothe chamber, thereby forming a metal layer with a predeterminedthickness by a PECVD method, wherein a supplying time of the hydrogengas is gradually increased.

Exemplary embodiments of the present invention provide a method offorming a metal layer with a predetermined thickness by a PECVD methodincluding alternately supplying a metal chloride compound gas and ahydrogen gas into a chamber into which a purge gas is continuouslysupplied at a predetermined flow rate, wherein a plasma reaction energyis gradually increased every time the hydrogen gas is supplied.

In another aspect of the present invention, exemplary embodiments of thepresent invention provide a method of fabricating a semiconductor deviceincluding forming a silicon conductive layer selectively exposed by aninterlayer insulating layer electrically insulating a semiconductorsubstrate having plural elements formed thereon; and alternatelysupplying a metal chloride compound gas and a hydrogen gas into achamber while a purge gas is supplied at a predetermined flow rate intothe chamber, thereby forming a metal layer with a predeterminedthickness by a PECVD method, wherein a plasma reaction energy isgradually increased every time the hydrogen gas is supplied.

Exemplary embodiments of the present invention provide a method offorming a metal layer with a predetermined thickness by a PECVD methodincluding alternately supplying a metal chloride compound gas and ahydrogen gas into a chamber into which a purge gas is continuouslysupplied at a predetermined flow rate, wherein a supplying time of thehydrogen gas is gradually increased and a plasma reaction energy isgradually increased every time the hydrogen gas is supplied.

In another aspect of the present invention, exemplary embodiments of thepresent invention provide a method of fabricating a semiconductor deviceincluding forming a silicon conductive layer selectively exposed by aninterlayer insulating layer electrically insulating a semiconductorsubstrate having plural elements formed thereon; and alternatelysupplying a metal chloride compound gas and a hydrogen gas into achamber while a purge gas is supplied at a predetermined flow rate intothe chamber, thereby forming a metal layer with a predeterminedthickness by a PECVD method, wherein a plasma reaction energy isgradually increased every time the hydrogen gas is supplied.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent to those of ordinary skill in the art bydescribing in detail preferred embodiments thereof with reference to theattached drawings in which:

FIG. 1 is a sectional view of a semiconductor device illustrating aconventional method of forming a metal layer;

FIG. 2 is a sectional view schematically illustrating a plasma-enhancedchemical vapor deposition apparatus used in the method of forming ametal layer according to the present invention;

FIG. 3 is a sectional view illustrating a contact pad structureresulting from a method for fabricating such a semiconductor deviceaccording to the present invention;

FIG. 4 is a flow chart schematically illustrating a method of forming atitanium layer according to a first embodiment of the present invention;

FIGS. 5 and 6 are graphs illustrating comparison of a distribution ofcontact resistances of a semiconductor device fabricated using themethod of forming the titanium layer according to a first embodiment ofthe present invention, and a distribution of contact resistances of thesemiconductor device fabricated by the conventional method of formingthe titanium layer using a mixture gas or a single gas only;

FIG. 7 is a flow chart schematically illustrating a method of forming atitanium layer according to a second embodiment of the presentinvention;

FIG. 8 is a graph illustrating a distribution of contact resistances ofa semiconductor device fabricated by a method of forming a titaniumlayer according to a second embodiment of the present invention;

FIG. 9 is a flow chart schematically illustrating a method of forming atitanium layer according to a third embodiment of the present invention;and

FIG. 10 is a flow chart schematically illustrating a method of forming atitanium layer according to a fourth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided asteaching examples of the invention. Like numbers refer to like elements.

FIG. 2 is a sectional view schematically illustrating a plasma-enhancedchemical vapor deposition (PECVD) apparatus used in the method offorming a metal layer according to the present invention.

Referring to FIG. 2, the PECVD apparatus includes a chamber 100 in whicha deposition process is performed. Reaction gases and purge gases aresupplied into the chamber 100 through a gas supply line 110. The gassupply line 110 supplies a purge gas such as argon (Ar), and a reactiongas such as a hydrogen (H₂) gas or a metal chloride gas. A shower head180 uniformly sprays the reaction gas or the purge gas, which isintroduced into the chamber 100 through the gas supply line 110, towarda semiconductor substrate 130 at a predetermined flow rate. The gasessupplied to the chamber 100 through the gas supply line 110 are measuredby a mass-flow controller when supplied. Further, a vacuum pump (notshown) is connected to the chamber 100 via an exhaust line 120 todecrease a pressure inside the chamber 100 and exhaust the gases thereinside out of the chamber 100.

A supporting table 140 for supporting the semiconductor substrate 130 islocated inside the chamber 100. Even though not shown in the drawing,the supporting table 140 may have a heater for controlling a temperatureof the semiconductor substrate. An upper electrode 170, which isconnected to a matching box 150 and a power source 160, is locatedinside the chamber 100 to induce a plasma reaction. The power source 160supplies about 50 to 900 W of power, for example, about 200 W at a lowfrequency of about 400 to 500 kHz, for example, about 460 kHz to theupper electrode 170. The power generated from the power source 160activates plasma reaction of reaction gases. By the plasma reaction, ametal layer such as a titanium layer is formed on the substrate, and thereaction by-products generated by the plasma reaction are removed out ofthe chamber 100 through a vent line 120 by pumping of a vacuum pump (notshown).

A method of fabricating a semiconductor device using the PECVD apparatusstructured as above will be explained as follows.

FIG. 3 is a sectional view illustrating a semiconductor device formedaccording to a method of the present invention.

As shown in FIG. 3, in the method of fabricating a semiconductor deviceaccording to the present invention, a conductive region 200 is formed byimplanting conductive impurity ions into the single crystal siliconsemiconductor substrate 130, or a contact pad (not shown) is formed tobe electrically connected to the semiconductor substrate 130, usingpolycrystal silicon formed by implanting the conductive impurity ions.An interlayer insulating layer 190 is formed on the overall surface ofthe semiconductor substrate 130 with a predetermined thickness, and aphotoresist pattern (not shown) is formed on the interlayer insulatinglayer 190 to selectively expose the interlayer insulating layer 190formed on the conductive region 200 or the contact pad. Using thephotoresist pattern as an etch mask, the interlayer insulating layer 190is removed, and the photoresist pattern is removed, thereby forming acontact hole 240 selectively exposing the conductive region 200 or thecontact pad by the interlayer insulating layer 190.

Then, a titanium layer 210 (referred to as a metal layer) with apredetermined thickness is formed on the semiconductor substrate 130having the contact hole 240 formed thereon, using a PECVD method. Atitanium nitride layer 220 is formed on the titanium layer 210, and atungsten layer 230 is formed on the titanium nitride layer 220, using aPECVD method or sputtering method.

Here, the titanium layer 210 forms a titanium silicide at the interfacewith the silicon conductive region 200 or the contact pad through thecontact hole 240, and reduces a contact resistance. For example, thetitanium layer 210 may be formed by supplying an argon gas as an inertgas, a titanium chloride (TiCl₄) gas as a reaction gas, and a hydrogengas to decompose titanium element from the titanium chloride gas(hereinafter, referred to as metal chloride compound) into the chamber100, with a thickness of about 100 Å.

The PECVD method is used to prevent diffusion of conductive impuritiesin the conductive region 200 and the channel region, and to preventdeterioration of semiconductor devices as would occur using a chemicalvapor deposition method as a high temperature process.

In order to form the titanium silicide to reduce a contact resistance atthe surface of the silicon conductive region 200 exposed by the contacthole 240 or the contact pad, heat is necessary to volatilize chlorineelement from the metal chloride compound as well as to expose the metalchloride compound to the hydrogen gas. In the meantime, in order toprevent bonding of silicon and hydrogen at the surface of the conductiveregion 200 or the contact pad, the hydrogen gas may not be used duringthe initial time of forming the titanium layer 210.

Accordingly, a method of forming the titanium layer 210 in use for thefabrication of semiconductor devices will now be explained withexemplary embodiments using a PECVD method employing a lower temperatureprocess than a CVD method.

FIG. 4 is a flow chart schematically illustrating a method of formingthe titanium layer 210 according to a first embodiment of the presentinvention.

As shown in FIG. 4, a mixture gas including hydrogen and metal chloridecompound (TiCl₄) and a purge gas are supplied concurrently for apredetermined time into the sealed chamber 100 (FIG. 2), thereby forminga first titanium layer on the exposed conductive layer of asemiconductor substrate 130 using a PECVD method (S100).

Here, the first titanium layer is composed of titanium silicide at theinterface of the conductive region 200 or the contact pad, and is formedwith a predetermined thickness at a temperature necessary to form metalsilicide.

For example, the first titanium layer may be formed with a thickness ofabout 30 Å by flowing an argon gas at about 300 sccm, a hydrogen gas atabout 2000 sccm, and a metal chloride compound gas at about 3 to 5 sccminside the chamber 100 for about 5 to 6 seconds. At this time, apressure of the chamber 100 is about 0.1 to 10 Torr, and a temperaturethereof is about 400 to 600° C., preferably about 450° C. Further, about200 W of RF power is applied through the upper electrode 170 during theprocess of forming the first titanium layer.

Then, supplying of the mixture gas into the chamber 100 is stopped for apredetermined time, and only argon gas is supplied into the chamber 100(S110).

Then, while the argon gas is continuously flowed into the chamber 100,the metal chloride compound gas is supplied for a predetermined time(S120). Then, supplying of the metal chloride compound gas is stopped,and only the argon gas is flowed into the chamber 100 for apredetermined time (S130). Then, while the argon gas is continuouslyflowed, the hydrogen gas is supplied for a predetermined time (S140) andthen stopped. Then, only the argon gas is flowed into the chamber 100for a predetermined time (S150), thereby forming a second titanium layeron the first titanium layer.

Finally, the hydrogen gas and the metal chloride compound gas arealternately supplied into the chamber 100 by a predetermined number oftimes until a thickness of the second titanium layer reaches apredetermined value (S160).

That is, the first titanium layer is formed using the mixture gasincluding the hydrogen gas and the metal chloride compound gas, and thesecond titanium layer is formed on the first titanium layer by supplyingthe hydrogen gas and the metal chloride compound gas alternately as asingle gas for a predetermined time while the purge gas is continuouslysupplied into the chamber 100, and during the operation, by allowing apurging time to flow only the argon gas inside the chamber 100 for apredetermined time for purging.

For example, the second titanium layer may be formed by repeatedlyperforming a following cycle by about 7 to 15 times, with a thickness ofabout 70 Å, and one cycle includes supplying the metal chloride compoundgas and the argon gas into the chamber 100 for about 10 to 20 seconds,supplying only the argon gas for about 10 to 20 seconds, supplying thehydrogen gas and the argon gas for about 10 to 20 seconds, and supplyingonly the argon gas for about 10 to 20 seconds. At this time, the secondtitanium layer may be formed with a temperature inside the chamber 100about 400 to 600° C., preferably about 450° C. Further, a pressure ofthe chamber 100 is about 0.1 to 10 Torr. The second titanium layer maybe formed with about 200 W of RF power like the first titanium layer.

FIGS. 5 and 6 are graphs illustrating comparison of a distribution ofcontact resistances of the semiconductor device fabricated using themethod of forming the titanium layer according to a first embodiment ofthe present invention, and a distribution of contact resistances of thesemiconductor device fabricated by the method of forming the titaniumlayer using a conventional mixture gas or a single gas only. As shown inthe drawings, the distribution (a) of contact resistances of thesemiconductor device fabricated using the method of forming the titaniumlayer according to a first embodiment of the present invention issuperior to the distributions (b, c, d) of contact resistances of thesemiconductor device fabricated by the method of forming the titaniumlayer using a conventional mixture gas or a single gas only.

In this graph, a transverse axis of the graph represents a dimension ofa contact resistance, and a vertical axis of the graph represents adistribution of a contact resistance, and superiority of a semiconductordevice is normally determined around about 50% of the distribution.

In the method of forming the titanium layer 210 according to a firstembodiment of the present invention, after the first titanium layer witha predetermined thickness is formed using a mixture gas including ahydrogen gas and a metal chloride compound gas, the second titaniumlayer is formed on the first titanium layer, by flowing the hydrogen gasand the metal chloride compound gas individually as a single gas with apredetermined time for purging. In the method of forming the titaniumlayer using a conventional mixture gas, a single titanium layer (b, c)is formed by selectively flowing a metal chloride compound gas duringthe flowing of a purge gas and a hydrogen gas, or a single titaniumlayer (d) is formed by flowing a hydrogen gas and a metal chloridecompound gas individually as a single gas for a predetermined time.

Therefore, the method of forming the titanium layer 210 according to afirst embodiment of the present invention further increases or optimizesa production yield than the conventional method using a CVD method,because the titanium layer 210 is formed using a low temperature PECVDmethod according to the present invention so as to prevent deteriorationof semiconductor devices due to a high temperature.

FIG. 7 is a flow chart schematically illustrating a method of forming atitanium layer according to a second embodiment of the presentinvention.

Referring to FIG. 7, the method of forming a titanium layer 210according to a second embodiment of the present invention includesflowing only an argon gas at a predetermined flow rate for apredetermined time (S200).

Then, while the argon gas is continuously flowed into the chamber 100, ametal chloride compound gas is supplied for a predetermined time (S210).Then, the supplying of the metal chloride compound gas is stopped, andonly the argon gas is flowed into the chamber 100 for a predeterminedtime (S220). Then, while the argon gas is continuously flowed, thehydrogen gas is supplied for a predetermined time (S230), therebyforming the titanium layer 210.

Then, the supplying of the hydrogen gas is stopped, and only the argongas is flowed into the chamber 100 for a predetermined time. The metalchloride compound gas and the hydrogen gas are alternately supplied intothe chamber 100 (S240) until the titanium layer 210 is formed with apredetermined thickness. At this time, the supplying time of thehydrogen gas is gradually increased as compared to the initial supplyingtime, so that the hydrogen gas is supplied into the chamber 100 (S230).

That is, while the argon gas is supplied into the chamber 100 at apredetermined flow rate by a CVD method, the metal chloride compound gasand the hydrogen gas are alternately supplied, in which the supplyingtime of the hydrogen gas is gradually increased to form the titaniumlayer 210 with a predetermined thickness.

For example, in order to form the titanium layer 210 with a thickness ofabout 100 Å, the metal chloride compound gas and the argon gas aresupplied into the chamber 100 for about 10 to 20 seconds, and then, onlythe argon gas is supplied for about 10 to 20 seconds. The hydrogen gasand the argon gas are supplied for about 5 seconds, and then, only theargon gas is supplied for about 10 to 20 seconds. The metal chloridecompound gas and the argon gas are supplied into the chamber 100 forabout 10 to 20 seconds, and then, only the argon gas is supplied forabout 10 to 20 seconds. Then, the hydrogen gas and the argon gas aresupplied for about 10 seconds, which is 5 seconds more than the initialtime, about 5 seconds, of supplying the hydrogen, and then, only theargon gas is supplied for about 10 to 20 seconds. The cycle is repeatedby about 7 to 15 times. At this time, the supplying time of the hydrogengas is gradually increased with every repetition. This process regulatesthe decomposition of the metal chloride compound formed on theconductive region 200 or the contact pad exposed through the contacthole 240 and formation of the titanium layer 210. Further, the titaniumlayer 210 may be formed with a temperature inside the chamber 100 atabout 400 to 600° C., preferably at about 450° C. Further, a pressure ofthe chamber 100 is about 0.1 to 10 Torr. The titanium layer 210 isformed with about 200 W of RF power applied.

FIG. 8 is a graph illustrating a distribution of contact resistances ofa semiconductor device fabricated by a method of forming a titaniumlayer according to a second embodiment of the present invention. Adistribution (e) of contact resistances of the semiconductor devicefabricated by a method of forming a titanium layer according to a secondembodiment of the present invention, in which the titanium layer 210 isformed while gradually increasing the supplying time of the hydrogen gasfrom the initial time, is superior to a distribution (f) of contactresistances of the semiconductor device fabricated by a method offorming the titanium layer 210 with the supplying time of the hydrogengas remaining constant.

In this graph, a transverse axis of the graph represents a dimension ofa contact resistance, and a vertical axis of the graph represents adistribution of a contact resistance, and superiority of a semiconductordevice is normally determined around about 50% of the distribution. Atthis time, when an initial titanium layer 210 is formed on theconductive region 200 or the surface of the contact pad, if a smallamount of hydrogen gas is flowed, the contact resistance is decreased.By exposing the conductive region 200 or the silicon of the contact padto the metal chloride compound gas first, a metal chloride compound isformed on the surface of the conductive region or the contact pad. Then,by exposing the metal chloride compound to the hydrogen gas, defects dueto hydrogen bonding on the surface of the conductive region 200 or thecontact pad can be prevented.

Therefore, the method of forming the titanium layer 210 according to asecond embodiment of the present invention can reduce a contactresistance of silicon and the titanium layer 210 by flowing a smalleramount of the hydrogen gas than the metal chloride compound gas duringthe formation of the initial titanium layer 210 so as to reduce thehydrogen bonding on the conductive region 200 or the silicon surface ofthe contact pad exposed by the contact hole 240, thereby to reducegeneration of defects. That is, the hydrogen gas can be flowed at 2000sccm for a much shorter time than the 3-5 sccm flow rate of the metalchloride so that the total amount of the hydrogen gas flowed during theformation of the initial titanium layer is smaller than the total amountof the metal chloride compound gas flowed during the formation of thesame layer.

FIG. 9 is a flow chart schematically illustrating a method of forming atitanium layer according to a third embodiment of the present invention.

Referring to FIG. 9, in the method of forming the titanium layer 210according to a third embodiment of the present invention, only the argongas is flowed at a predetermined flow rate inside the chamber 100 for apredetermined time with a predetermined RF power (S300). For example,about 200 W of RF power is applied to the upper electrode 170 to induceplasma reaction inside the chamber 100.

Then, while the argon gas is continuously flowed into the chamber 100,the metal chloride compound gas is supplied for a predetermined time(S310). Then, the supplying of the metal chloride compound gas isstopped, and only the argon gas is flowed into the chamber 100 for apredetermined time (S320). In the same way, about 200 W of RF power isapplied to the upper electrode 170 to induce plasma reaction inside thechamber 100. Then, the argon gas is continuously flowed, and thehydrogen gas is supplied for a predetermined time (S330) to form thetitanium layer 210. At this time, about 50 W of RF power is applied tothe upper electrode 170, so as to induce plasma reaction inside thechamber 100. Therefore, the plasma reaction at a low energy during thesupplying of the hydrogen gas reduces the reaction by the hydrogen gason the conductive region 200 or the silicon surface of the contact pad,thereby to reduce defects due to the hydrogen bonding on the siliconsurface.

Then, the supplying of the hydrogen gas is stopped, and only the argongas is flowed into the chamber 100 for a predetermined time. The metalchloride compound gas and the hydrogen gas are alternately supplied intothe chamber 100 until the titanium layer 210 is formed with apredetermined thickness (S340). At this time, the RF power during thesupplying of the hydrogen gas is gradually increased more than at theinitial supplying.

That is, while alternately supplying the metal chloride compound gas andthe hydrogen gas into the chamber 100, in which a purge gas at apredetermined flow rate is supplied, using a PECVD method with apredetermined RF power, the RF power is lower during the initialsupplying of the hydrogen gas than during the supplying of other gases,but the RF power is gradually increased every time of supplying thehydrogen gas after the initial supplying, thereby to form the titaniumlayer 210 with a predetermined thickness.

For example, in order to form the titanium layer 210 with a thickness ofabout 100 Å, the metal chloride compound gas and the argon gas aresupplied into the chamber 100 for about 10 to 20 seconds with about 200W of RF power, and then, only the argon gas is supplied for about 10 to20 seconds. The hydrogen gas and the argon gas are supplied for about 10to 20 seconds of an initial supplying time with about 50 W of RF power,and then, only the argon gas is supplied for about 10 to 20 seconds withabout 200 W of RF power. The metal chloride compound gas and the argongas are supplied into the chamber 100 for about 10 to 20 seconds, andthen, only the argon gas is supplied for about 10 to 20 seconds. Then,the hydrogen gas and the argon gas are supplied for about 10 to 20seconds with about 100 W of RF power, which is 50 W higher than theabout 50 W of initial RF power, and then, only the argon gas is suppliedfor about 10 to 20 seconds with about 200 W of RF power. The cycle isrepeated by about 7 to 15 times. At this time, the supplying time of thehydrogen gas is maintained same as the initial supplying time, but theRF power is gradually increased in subsequent steps. This processregulates the decomposition of the metal chloride compound formed on theconductive region 200 or the contact pad exposed through the contacthole 240, and formation of the titanium layer 210. Further, the titaniumlayer 210 may be formed inside the chamber 100, inner temperature ofwhich is about 400 to 600° C., preferably about 450° C. Further, apressure of the chamber 100 is about 0.1 to 10 Torr. The titanium layer210 formed on the conductive region 200 or the contact pad may beconverted to titanium silicide by chemical bonding of silicon andtitanium.

Therefore, the method of forming the titanium layer 210 according to athird embodiment of the present invention can reduce a contactresistance of silicon and the titanium layer 210 by applying a lower RFpower while supplying of the hydrogen gas into the chamber 100 duringinitial formation of the titanium layer 210 than during supplying of themetal chloride compound gas, so as to reduce the hydrogen bonding at thesilicon interface of the conductive region 200 or the contact padexposed by the contact hole 240, thereby to reduce generation ofdefects.

FIG. 10 is a flow chart schematically illustrating a method of forming atitanium layer according to a fourth embodiment of the presentinvention.

Referring to FIG. 10, in the method of forming the titanium layer 210according to a fourth embodiment of the present invention, only theargon gas at a predetermined flow rate is flowed into the chamber 100for a predetermined time (S400). About 200 W of RF power is applied tothe upper electrode 170 to induce plasma reaction inside the chamber100.

Then, while the argon gas is continuously flowed into the chamber 100,the metal chloride compound gas is supplied for a predetermined time(S410). Then, the supplying of the metal chloride compound gas isstopped, and only the argon gas is flowed into the chamber 100 for apredetermined time (S420). In the same way, about 200 W of RF power isapplied to the upper electrode 170 to induce plasma reaction inside thechamber 100. Then, while the argon gas is continuously flowed, thehydrogen gas is supplied for a predetermined time with a predeterminedRF power applied (S430), thereby to form the titanium layer 210. Forexample, about 50 W of RF power is applied to the upper electrode 170,and the hydrogen gas is flowed for about 5 seconds. Thus, the plasmareaction at a low energy during the supplying of the hydrogen gasreduces reaction by the hydrogen gas on the conductive region 200 or onthe silicon surface of the contact pad, and by flowing the hydrogen gasfor a shorter time than during the flowing time of the metal chloridecompound gas, defects due to hydrogen bonding at the silicon interfacecan be reduced.

Then, the supplying of the hydrogen gas is stopped, and only the argongas is flowed into the chamber 100 for a predetermined time. The cycleis repeated by a predetermined number of times until a thickness of thetitanium layer 210 reaches a predetermined value, and thus, the metalchloride compound gas and the hydrogen gas are alternately supplied intothe chamber 100 (S440). At this time, the hydrogen gas is supplied intothe chamber 100 while the RF power is gradually increased during thesupplying of the hydrogen gas as compared to the initial supplying step.

That is, while the argon gas at a predetermined flow rate is suppliedinto the chamber 100, the metal chloride compound gas and the hydrogengas are alternately supplied into the chamber 100 by a PECVD method toform the titanium layer 210 with a predetermined thickness. Here, thehydrogen gas is supplied at the initial supplying step with a low RFpower and a short supplying time, and then, the RF power and thesupplying time are increased every supplying step of the hydrogen gasafter the initial supplying step.

For example, the metal chloride compound gas and the argon gas aresupplied into the chamber 100 for about 10 to 20 seconds with about 200W of RF power, and then, only the argon gas is supplied for about 10 to20 seconds. The hydrogen gas and the argon gas are supplied for about 5seconds with about 50 W of RF power, and then, only the argon gas issupplied for about 10 to 20 seconds with about 200 W of RF power. Themetal chloride compound gas and the argon gas are supplied into thechamber 100 for about 10 to 20 seconds, and then, only the argon gas issupplied for about 10 to 20 seconds. The hydrogen gas and the argon gasare supplied for about 10 seconds, about 5 seconds more than the initialsupplying time, with about 100 W of RF power, about 50 W more than theinitial RF power, and then, only the argon gas is supplied for about 10to 20 seconds with about 200 W of RF power. The above cycle is repeatedby about 7 to 15 times to form the titanium layer 210 with a thicknessof about 100 Å. At this time, the supplying time of the hydrogen gas andthe RF power applied during the supplying of the hydrogen gas aregradually increased in subsequent steps. This process regulates thedecomposition of the metal chloride compound formed on the conductiveregion 200 or the contact pad exposed through the contact hole 240, andformation of the titanium layer 210. Further, the titanium layer 210 maybe formed inside the chamber 100, inner temperature of which is about400 to 600° C., preferably about 450° C. Further, a pressure of thechamber 100 is about 0.1 to 10 Torr. The titanium layer 210 formed onthe conductive region 200 or the contact pad may be converted totitanium silicide by chemical bonding of silicon and titanium.

Therefore, the method of forming the titanium layer 210 according to afourth embodiment of the present invention can reduce a contactresistance of silicon and the titanium layer 210 by applying a lower RFpower and a shorter supplying time during supplying of the hydrogen gasinto the chamber 100 during initial formation of the titanium layer 210than during supplying of the metal chloride compound gas, so as toreduce the hydrogen bonding at the silicon surface of the conductiveregion 200 or the contact pad exposed by the contact hole 240, therebyto reduce generation of defects.

Further, the description of the exemplary embodiments as above has beenmade to provide better and more complete understanding of the presentinvention with reference to the attached drawings, but it must not beunderstood to limit the present invention. For example, the presentinvention also includes reducing the supplying amount of the hydrogengas as a decomposition gas of a metal compound during formation of ametal layer formed on the silicon of the conductive region 200 or thecontact pad, or reducing a RF power required for plasma reaction,thereby to prevent the hydrogen bonding on the silicon surface.

As described above, according to the present invention, a titanium layeris formed using a low temperature process of a PECVD method rather thanthe conventional CVD method, thereby to prevent deterioration ofsemiconductor devices due to a high temperature, and increase oroptimize a production yield.

Further, the hydrogen gas is supplied during formation of the initialtitanium layer at a lower float rate than the flow rate of the metalchloride compound gas, and plasma reaction energy every time ofsupplying the hydrogen gas is reduced to reduce the hydrogen bonding onthe silicon surface of the conductive region or the contact pad exposedby the contact hole, and to reduce defects, thereby reduce the contactresistance of the silicon and the titanium layer.

The invention has been described using preferred exemplary embodiments.However, it is to be understood that the scope of the invention is notlimited to the disclosed embodiments. On the contrary, the scope of theinvention is intended to include various modifications and alternativearrangements within the capabilities of persons skilled in the art usingpresently known or future technologies and equivalents. The scope of theclaims, therefore, should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

1. A method of forming a metal layer with a predetermined thickness by aPECVD method comprising: alternately supplying a plurality of times ametal chloride compound gas and a hydrogen gas into a chamber;continuously supplying a purge gas into the chamber at a predeterminedflow rate; applying a plasma reaction energy during the hydrogen gassupply steps; and gradually increasing the plasma reaction energyapplied in each subsequent hydrogen supply step.
 2. The method accordingto claim 1, when the hydrogen gas and the metal chloride compound gasare alternately supplied into the chamber, the method further comprisingsupplying only the purge gas for a predetermined purge time between thesupplying of the hydrogen gas and the supplying of the metal chloridecompound gas.
 3. The method according to claim 2, wherein the purge timeis about 10 to 20 seconds.
 4. The method according to claim 1, whereinthe purge gas is supplied into the chamber at a flow rate of about 300sccm.
 5. The method according to claim 1, wherein the metal chloridecompound gas, which is supplied into the chamber alternately with thehydrogen gas, is supplied at a flow rate of about 3 to 5 sccm for about10 to 20 seconds.
 6. The method according to claim 1, wherein thehydrogen gas, which is supplied into the chamber alternately with themetal chloride compound gas, is supplied at a flow rate of about 2000sccm for about 10 to 20 seconds at an initial time.
 7. The methodaccording to claim 1, wherein 50 W of plasma reaction energy is appliedwhen the hydrogen gas is supplied into the chamber at an initial time.8. The method according to claim 7, wherein, when the hydrogen gas issupplied into the chamber, the plasma reaction energy is increased ineach subsequent hydrogen supply step by about 50 to 100 W from theplasma reaction energy applied when the hydrogen gas is supplied at aninitial time.
 9. The method according to claim 1, wherein the metallayer is formed by applying 200 W of plasma reaction energy when themetal chloride compound gas or the purge gas only is supplied into thechamber.
 10. A method of fabricating a semiconductor device comprising:forming a silicon conductive layer selectively exposed by an interlayerinsulating layer electrically insulating a semiconductor substratehaving plural elements formed thereon; and alternately supplying a metalchloride compound gas and a hydrogen gas into a chamber while a purgegas is supplied at a predetermined flow rate into the chamber, therebyforming a metal layer with a predetermined thickness by a PECVD method,wherein a plasma reaction energy is gradually increased every time thehydrogen gas is supplied.
 11. The method according to claim 10, when thehydrogen gas and the metal chloride compound gas are alternatelysupplied into the chamber, the method further comprising supplying onlythe purge gas for a predetermined purge time between the supplying ofthe hydrogen gas and the supplying of the metal chloride compound gas.12. The method according to claim 11, wherein the purge time is about 10to 20 seconds.
 13. The method according to claim 10, wherein the purgegas is supplied into the chamber at a flow rate of about 300 sccm. 14.The method according to claim 10, wherein the metal chloride compoundgas, which is supplied into the chamber alternately with the hydrogengas, is supplied at a flow rate of about 3 to 5 sccm for about 10 to 20seconds.
 15. The method according to claim 10, wherein the hydrogen gas,which is supplied into the chamber alternately with metal chloridecompound gas, is supplied at a flow rate of about 2000 sccm for about 10to 20 seconds at an initial time.
 16. The method according to claim 10,wherein 50 W of plasma reaction energy is applied when the hydrogen gasis supplied into the chamber at an initial time.
 17. The methodaccording to claim 16, wherein, when the hydrogen gas is supplied intothe chamber, the plasma reaction energy is increased by about 50 to 100W from the plasma reaction energy applied when the hydrogen gas issupplied at an initial time.
 18. The method according to claim 10,wherein the metal layer is formed by applying 200 W of plasma reactionenergy when the metal chloride compound gas or the purge gas only issupplied into the chamber.